Physical properties

thumb|Example of a dissolved solid (left) thumb|upright|Formation of crystals in a 4.2 Molar concentration|M [[ammonium sulfate solution. The solution was initially prepared at 20 °C and then stored for 2 days at 4 °C.]]

In materials science, hardness (antonym: softness) is a measure of the resistance to plastic deformation, such as an indentation (over an area) or a scratch (linear), induced mechanically either by pressing or abrasion. In general, different materials differ in their hardness; for example hard metals such as titanium and beryllium are harder than soft metals such as sodium and metallic tin, or wood and common plastics. Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, hardness can be measured i

thumb|Tensile test of an Aluminium–magnesium–silicon alloys|Al-Mg-Si alloy. The local necking and the cup and cone fracture surfaces are typical for ductile metals. thumb|This tensile test of a Ductile iron|nodular cast iron demonstrates low ductility.

tendency of matter to change volume in response to a change in temperature

property of an object or substance to transmit light with minimal scattering

attribute of a physical system or body; OR non-chemical property of a material

optical property describing the ability of a surface to reflect light in a specular direction

thumb|Brittle fracture in glass thumb|Brittle fracture in cast iron tensile testpieces A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Breaking is often accompanied by a sharp snapping sound.

thumb|250px|right|Comparisons of 1. opacity, 2. translucency, and 3. transparency; behind each panel is a star. Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer, it describes the absorption and scattering of radiation in a medium, such as a plasma, dielectric, shielding material, glass, etc. An opaque object is neither transparent nor translucent. When light strikes an interface between two substances, in general, some may be reflected, some absorbed, some scattered, and the rest transmitted (also see refr

A dopant (also called a doping agent) is a small amount of a substance added to a material to alter its physical properties, such as electrical or optical properties. The amount of dopant is typically very low compared to the material being doped.